I have 2014 CAT 299D s/n: GTC01423. It has recently started derating itself. It cranks up and runs fine and then starts throwing codes 636-2 and 3509-4. It will run fine unless you start running the throttle at higher rpm. I have checked the 1150ohm resistor on the engine harness and I have 5 voltage on the plugs. I have pulled the harness and haven't found any concerning damage. The last step in the test procedure I found says if the problem is intermittent the damage is in the harness and to replace it... any insite before I purchase a new harness??? It will take me a week or more to get because of my location.
Attached are the two troubleshooting procedures for the Codes your machine is setting. Personally I would suggest to do the Sensor power supply test first. Post back if Step 2 of the speed/timing test results in a "Not OK" result.
I have already done the test procedure for the 636-2 code, everything checked out fine. last step says replace the harness. On the 3509-4 code im not sure how to go about testing the voltage at the ecm because it's mounted really tight beside the engine and has minimal access
So the Test Step 2 result was "OK".? TBH this is the same as when a procedure recommends an ECM replacement. You do the procedure over again, probably more than once, to make sure the diagnosis is correct. These engine harnesses are known to fail. There is indication that in at least one place the harness is routed too tighly at the factory around a 90-Deg bend and the individual wires can fail internally with no indication on the outside of the harness that anything is amiss. You will need to fabricate something to get into the pins if spoons for your DMM won't get into the partciular location. Sometimes a paperclip can be a useful tool to get into the back side of a multi-pin connector to make contact with the pins inside.
I think I might have found the culprit... I have found 4 broken wires going to the round plug on the cab harness side of the round plug that connects the engine harness to the and the other round plug next to it
That looks as though someone has been in there before you. What’s under all that insulating tape.?
I was thinking the same thing. Nothing appears to be tampered with
Was this under the cab I'm having the 3509-4 code and I'm confused on how to test the ecm harness for 5v. And you are the only one that I have read everywhere that is having the same throttle problem that I am having. So I was hoping this fixed you problem.
Have you carried out the "Sensor Supply - Test" procedure as per the attachment in Post #2 above.? What were the results.?
That's where i'm confused at i don't know what the Terminal 40 (ground) / 60 (ground) is. I can fix anything but when it comes to wiring that is where it gets hard for me unless I have a video or someone to show me. Thanks for getting back to me i really do appreciate it
I think you had better start with a Serial Number to identify the correct electrical schematic.
Perfect didn't even think of that just thought they'd be the same I'll do that right now thank you
Unfortunately they are not all the same. In fact some Serial Number prefixes even have different schematics depending on Serial Number. The last 8 characters of the Product Identification Number is all you need.